FIG. 6 is a diagram illustrating an example of a connection with a server in a general Redundant Arrays of Inexpensive Disks (RAID) device.
The RAID device 1000 illustrated in FIG. 6 includes two redundant controller modules (CMs) 1010a and 1010b. In addition, a server 2000 is connected to the CM 1010a in the two CMs 1010a and 1010b. 
In order to operate the RAID device by using the redundancy of the CMs 1010a and 1010b, for example, it is preferable that both of the two CMs 1010a and 1010b transition to a power-on state when receiving a power-on instruction from a switch (not illustrated) or the server 2000.
However, the CM 1010b, which is not connected to the server 2000, cannot receive the power-on instruction from the server 2000. Therefore, there is a need for a control (power matching) that matches power states between the two CMs 1010a and 1010b. 
Patent Document 1: Japanese Laid-open Patent Publication No. 2006-106980
Patent Document 2: Japanese Laid-open Patent Publication No. 2007-122437
However, a storage device with a conventional method of matching power between CMs is started, stopped, and restarted by an operation of an operator. Thus, a power on/off signal is abnormally transferred between the CMs by an unexpected operation, and a power-on operation unintended by an operator occurs.